There Fabro comments that Aquinas was originally directly dependent on the "extrinsicist" metaphysics of Avicenna, but that in his mature works he appealed to the notion of the primacy of act by means of the notion of participation in two steps: (1) a pure and separate perfection can only be one, and esse is the first perfection and the act of all acts; therefore subsisting esse can only be one; (2) creatures are beings by participation insofar as their essences participate in esse, and so essence is potency with respect to esse, the first and ultimate act of each reality.
In my view this distinction between participating in esse commune and in esse subsistens is very important within Aquinas's theory of transcendental participation, and is something that Fabro did not bring out quite as explicitly as one might have wished in his truly groundbreaking works on participation.
Presently, I note that even if it were used this way (that is, as equivalent to "esse intelliligibile"), we still could not conclude from this usage that esse intentionale as such is the criterion of cognizance, since in the case of the angel the esse intentionale in question exists at the same time in esse immateriali.
22) Any existence in an intellect is existence in esse intelligibili.
So, for example, a stone has material existence in esse naturali; an angel has immaterial existence in esse naturali; an "intentio" in the medium has material existence in esse intentionali; (27) and, a cognitive species has (grades of) immaterial existence in esse intentionali.
The immateriality of intellect, then, in esse intelligibili, is presented as having attained a higher degree of perfection, completeness, or fullness of being.
it therefore results that all things other than God are not their esse, but share in esse; and so it is necessary that all things, which are diversified according to a diverse participation in esse, in such a way that they are more or less perfectly, (81) be caused by a first being (ens) which is in a most perfect way.
As Thomas indicates a few pages later, the substantial esse of a thing is nothing other than the esse that it has in virtue of its substantial form: "Prima perfectio ignis consistit in esse quod habet per suam formam substantialem"; STh I, q.
Where Boethius differs from Victorinus is, first of all, in allowing that id quod est participates in esse
In other words, he has now extended the limitation principle once more to that which participates in esse, since such a thing can do so only to the degree marked out for it by its nature or essence and, therefore, only to a finite degree.
However, if something possesses the infinite power to exist (infinitam virtutem ad essendum) only according to an esse that is participated in from something else, insofar as it participates in esse, it is finite.
Other existents only participate in esse in limited fashion.